A prospective randomised single-blind study of the effects of real and sham acupuncture on exercise-induced asthma was conducted in nineteen children. Forced expiratory flow in 1st second (FEV1), forced vital capacity (FVC), and peak expiratory flow rate (PEFR) were measured throughout acupuncture and after treadmill exercise. Neither real nor sham acupuncture affected the basal bronchomotor tone but both, when applied 20 min before exercise, attenuated exercise induced asthma: mean maximum percentage falls in FEV1, FVC, and PEFR were 44.4%, 33.3%, and 49.5% without acupuncture; 23.8%, 15.8%, and 25.9% after real acupuncture; and 32.6%, 26.1%, and 34.3% after sham acupuncture. Real acupuncture provided better protection against exercise-induced asthma than did sham acupuncture (p less than 0.05).